1. Technical Field
The present disclosure mainly relates to solder material of solder paste or the like used in soldering in an electronic circuit board, and a bonded structure using the solder material.
2. Background Art
For soldering an electronic circuit board and an electronic component to each other, solder material having a composition of Sn—Ag—Bi—In consisting of four types of elements is used, which is disclosed in, for example, Patent Literatures 1 and 2. In such solder material, thermal fatigue properties with respect to fatigue fracture occurring due to thermal stress accompanied by a temperature change are enhanced by a technique using an effect of solid solution. The solid solution denotes a technique of preventing deterioration of solder material by replacing a part of metal atoms arranged in a lattice with a different metal atom so as to distort such a lattice.